The subject matter herein relates generally to electrical connectors that have signal conductors configured to convey data signals and ground structures that provide a ground return path, reduce crosstalk between the signal conductors, and/or control impedance.
Communication systems exist today that utilize electrical connectors to transmit data. For example, network systems, servers, data centers, and the like may use numerous electrical connectors to interconnect the various devices of the communication system. Many electrical connectors include signal conductors and ground structures that are positioned between the signal conductors. The ground structures provide return current paths, mitigate crosstalk between the signal conductors, and control impedance. Examples of such ground structures include elongated ground conductors and ground shields.
As one example, a known communication system includes electrical connectors mounted to daughter cards that are configured to engage header connectors mounted to a backplane. The electrical connector includes a plurality of contact modules that are stacked side-by-side. Each contact module includes signal conductors, ground conductors, and at least one ground shield. The signal conductors are arranged in signal pairs and the ground conductors are positioned between adjacent signal pairs. The signal and ground conductors may be arranged in a ground-signal-signal-ground (GSSG) pattern such that the signal and ground conductors are aligned in a common plane. The ground shield electrically shields the signal and ground conductors of one contact module from the signal and ground conductors of another conductor. The ground shield also provides a return path and controls impedance of the electrical connector.
As another example, a known input/output (I/O) connector is configured to receive a pluggable small-form factor (SFF) module. The I/O connector includes a connector housing that forms a slot for receiving a circuit board from the pluggable SFF module. The I/O connector includes one or more rows of conductors in which each conductor engages a corresponding contact pad of the circuit board. The conductors include signal and ground conductors and may be arranged in a ground-signal-signal-ground (GSSG) pattern for each row.
There has been a general demand to increase the density of signal conductors within the electrical connectors and/or increase the speeds at which data is transmitted through the electrical connectors. As data rates increase and/or distances between the signal pairs decrease, however, it becomes more challenging to maintain a baseline level of signal quality. For example, the ground structures (e.g., the ground conductors and/or ground shields) may form surface waves that propagate between different points of the ground structures. The surface waves may be repeatedly reflected and form a resonating condition (or standing wave) that causes electrical noise. Depending on the frequency of the data transmission, the electrical noise may increase return loss and/or crosstalk and reduce throughput of the electrical connector.
Although techniques for dampening electrical resonance exist, the effectiveness and/or cost of implementing these techniques is based on a number of variables, such as the geometries of the connector housing, the signal and ground conductors, and the ground shields. For some applications and/or electrical connector configurations, alternative methods for controlling resonance along the ground structures may be desired.
Accordingly, there is a need for electrical connectors that reduce the electrical noise caused by resonating conditions in ground structures.